Blast Disease A Major Threat To Food Security: A Review Of Pathogen And Strategies To Control

Rice blast is caused by the fungi Magnaporthe oryzae, which belongs to the group Ascomycota. The disease cycle of rice blast begins with the infection of the plant tissue by the spores of the pathogen. The spores can be carried by wind, water, and insects, and can infect the plant at any growth stage, from seedling to the heading stage. Once the spore lands on the plant tissue, they germinate and penetrate the tissue through a specialized structure called appressoria. Inside the plant tissue, the fungus grows and produces lesions that appear as small grayish-white spots on the leaves, collar, neck, and panicle of the plant. Under favorable conditions, the lesions can enlarge rapidly, causing complete crop failure. The epidemiology of rice blasts is influenced by various factors, such as temperature, humidity, rainfall, wind, and varietal susceptibility. The pathogen can survive in the soil and plant debris for several months, providing a potential source of infection for the next crop. Several management strategies have been developed to control rice blasts, including cultural, botanical, nutrient management, biotechnological, and chemical methods. Chemical methods such as fungicides can be used to control the disease, but their use should be judicious to avoid the development of fungicide resistance and environmental pollution.